Greg Fredericks Naturopath

Can Your Shoes Affect Infertility and Cancer?

Greg Fredericks ND, NMD. © 2018.

Is it possible that we have taken for granted something that has a significant effect on our health lying beneath our feet?

The idea that the shoes a person wears could have implications on one’s health would probably sound ludicrous to most people but it has long been known that the soles of our feet are highly sensitive and can absorb what they come in contact with.

Holistic practitioners and medical doctors from the past used to prescribe the administering of iodine to the soles of their patients feet to cure goiters and underactive thyroid conditions.

Experiments with garlic cloves on the soles of the feet can result in “garlic breath” on the participant within one hour of application.

reflexology chart

Chinese medicine doctors, reflexologists and acupuncturists have mapped the bottom of the human feet for centuries and know the influences it has on certain organs. The use of ionic foot baths and other herbal patches have also demonstrated an ability to draw toxins and heavy metals from the soles of human feet.


While recent decades has made most people conscious of environmental xenoestrogens found in plastic drink containers, linings of tin cans and food substances, there may be something we have overlooked… our shoes!

It may not be just the inexpensive rubber/plastic shoes one wears to the beach but also in those leather shoes that contain synthetic linings.

Bisphenols including bisphenol A, S and F are all potential mutagenic, carcinogenic hormone/gene disrupters that are linked to obesity, diabetes, heart disease and cancer.

These substances have demonstrated an ability to affect gene transcription codes and cause biotransformation of human cells including infertility. (Eladak et al. 2015), (Michalowicz et al. 2014), (Chen et al. 2002).

Why Non-synthetic Shoes?

Often people think that as long as they wear leather shoes they are exempt from these influences; however the synthetic linings and insoles may be causing significant changes in one’s health. Most bisphenols are released in greater abundance when heat has been added. This has been shown with plastic drink bottles, but what about the content in plastic and synthetic rubber soles?  Is it possible that the feet can have sufficient elevation of temperatures on hot days to increase the absorption of these potential toxins?
BPAs have demonstrated a disruption of hormone signaling and even reproductive function, and this raises a concern that ubiquitous BPA exposure is negatively affecting the health of entire ecosystems and human populations. Research performed on animals at the University of Illinois has shown that varying degrees of exposure of BPAs can cause delay in reproductive organs and transgender effects (Larson et al. 2015).

Another synthetic substance commonly found in imitation leather shoes is a polyurethane derived substance called “poromeric” (coined by Du Pont) and found in leatherette and PVC/acrylate compositions. Sports shoes are known to contain Ethylene-vinyl acetate, polyurethane, isoprene and other plastic/vulcanised rubber compounds which combine isocyanate and polyol together with sulfur atoms to create the synthetic materials used. Within these composites are individual constituents such as phthalates from PVC which are used to make synthetic plastics more flexible. These amongst other polyurethane and formaldehyde compounds all have a long history of carcinogenesis or ability to cause cancer tumors. (Salmon et al. 1991) (Mikoczy et al. 2003). Phthalates have also been implicated in numerous test studies to be potent endocrine disrupters (Rudeletal.2009).

Other synthetic materials such as benzene derivatives are used in the manufacturing of synthetics .Benzenes have a long history of immune disregulation activity (Gillis et al. 2007) and has been implicated in genomic instability and epigenetic abnormalities leading to the generation of leukemic stem cell evolution and proliferation (McHale et al. 2012).

These before mentioned studies clearly demonstrate the adverse effects of synthetics on human cellular structures. The current infertility epidemic may be tangibly linked to these types of compounds. Epidemiological enquiries have continued to demonstrate a lowered testosterone level in human testes as well as mutagenic and genotoxic activity of BPA’s, formaldehydes, PCV’s, benzenes and other non-naturally derived compounds.

The Rise Endocrine Disrupting Chemicals (EDCs)

The effects of synthetic chemicals as endocrine disruptors have been established from research studies. Endocrine-disrupting chemicals (EDCs) were originally thought to exert actions primarily through nuclear hormone receptors, including estrogen receptors (ERs), androgen receptors (ARs), progesterone receptors, thyroid receptors (TRs), and retinoid receptors, among others. However new evidence has found that other receptors systems including neurotransmitter receptors such as serotonin, dopamine, orphan, norepinephrine receptors as well as enzyme pathways and others all have influence on homeostatic hormone balance (Diamanti-Kandarakis et al. 2009).

Two ubiquitous synthetic substances known as PFAS perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have been classified as toxic and removed from consumer products in the US in the early 2000s. However since then the industry continues to develop many more in fact over 4,700 types of PFAS were known to exist by 2018 and continue to rise as industry invents more new forms. A 2015 report by the US Center for Disease Control found that PFAs were detected in the blood of 97% of Americans.  Most PFAs and PFOAs are found in non stick cookware, luggage, carpets, furniture, food packaging, and stain resistant clothing and is now considered a “forever chemical” also in synthetic type footwear.

Not Just Xenoestrogen Endocrine Imbalances

Potential for many forms of disorders and hormone imbalances may include: low testosterone, polycystic ovarian syndrome, endometriosis and fibroids, low IQ, gestational diabetes and insulin resistance, gonad underdevelopment, poor semen quality, obesity, male breasts, and breast and testicular cancers and more.

Most of the before mentioned synthetic substances can also be classified as having xenoestrogenic activity in that they have the ability to bind to estrogen receptors. Not only can this affect aromatase polymorphisms (metabolic changes in hormone balance) but also potentiate critical points in carcinogenic pathways.  Exposure to xenoestrogens has been well documented and found to affect particular organ systems in addition to the usual endocrine / reproductive system. These include; breast, lung, kidney, pancreas, and brain. The results of one study found; a significant correlation between exposure to xenoestrogens and increased, gender-related, cancer risk and a need to re-evaluate agents so far defined as endocrine disruptors, as they are also key molecules in carcinogenesis (Fucic et al. 2012).

Most manufacturers believe that the toxic compounds are safe as long as they are within a solid rubber or plastic polymer. Unfortunately manufactures do not always consider the effects of heat and sweat in the promotion or absorption of synthetic toxins. It is interesting that the countries less likely to produce shoes with synthetic linings are Israel, Italy, Spain, Thailand, Turkey and the USA. Most of these shoes are worn by the elite, including royalty and high profile billionaires.

Vegan Friendly Shoes

Guilt can be a powerful marketing tool in motivating consumer choices. The new popular “vegan friendly” shoes that are currently being marketed as “animal friendly” turn out to be mostly manufactured from manmade synthetic materials that resemble leather. Interestingly people who wear animal derived leather shoes are not considered to be vegans regardless of their diet. If the shoes look like leather, feel like leather but has no smell of leather, it probably is not leather. Shoes constructed from alternative plant based material such as hemp are now in development but so far do not demonstrate durability. 

As for the rest of the population, statistics on rising health conditions including diabetes, infertility, heart disease, and cancer continue to soar. With the scientifically proven effects of xenoestrogenic and genotoxicity on the multifaceted human receptor systems could humanity be in store for more disruption? With the significant increases in transgender related hermaphroditic births and the current infertility epidemic affecting 186 million people annually (according to the World Health Organization), could there be a ubiquitous influence right under our feet?


Eladak S. et al. “A new chapter in the bisphenol A story: bisphenol S and bisphenol F are not safe alternatives to this compound.” Fertility and Sterility Vol103, Issue 1, January 2015, 11-21(PubMed).

Michalowicz J. “Bisphenol A Sources, toxicity and biotransformation” Environmental Toxicity and Pharmacology Vol 37, Issue 2, March 2014, 738-58.

Chen MY. Acute toxicity, mutagenicity, and estrogenicity of bisphenol A and other bisphenols Environmental toxicology Jan 2002, Vol 17 (1) 80-86.

Larson GD et al. Transgender effects of BPA Labanimal 44, 104 (2015).

Salmon AG, Zelse L. Risks of Carcinogenesis from Urethane Exposure CRC Press 1991: Boca Raton Florida 33431.

Gillis B. et al Identification of Human Cell Responses to Benzene and Benzene Metabolites. Genomic Vol90 (3) Sept 2007, P.324-333 (PubMed).

McHale CM et al. Current understandings of the mechanism of benzene-induced leukemia in Humans implications for risk. Carcinogenesis, Vol 33(2) Feb 2012 P 240-52 (PubMed).

Diamanti-Kandarakis E, Bourguignon J-P, Giudice LC, Hauser R, Prins GS, Soto GS, Zoeller RT, Gore AC. Endocrine-Disrupting Chemical: An Endocrine Society Scientific Statement. Endocrine Review. 2009 June, 30 (4): 293-342 (PubMed).   

Fucic A, Gamulin M, Ferencic Z, Katic J, von Krauss MK, Bartonova A, Merlo DF.  Environmental exposure to xenoestrogens and oestrogen related cancers: reproductive system, breast, lung, kidney, pancreas and brain. Environmental Health Vol. 11, article no. S8, June 2012.

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